Force meter
The primary application of this force meter is measurement of fluid flow. A force on the force sensor push the force sensor away from the original position. The deviation of the force sensor is detected by a proximity sensor. An electronic unit takes the position signal from the proximity sensor as a feedback. The electronic unit generates electric current to an electromagnetic anti-torque means. The electromagnetic anti-torque means generates an anti-torque on force sensor to prevent the force sensor from moving away from the original position. A display unit measures the electric current and calculates velocity and rate of fluid before displays the results.
This application is a continuation-in-part of U.S. application Ser. No. 11/546,851, filed Oct. 13, 2006, now U.S. Pat. No. 7,611,472
BACKGROUND OF THE INVENTIONA flow meter using turbine is not as accurate to low velocity flow due to large inertia of the turbine and significant friction at the axle of the turbine. It is not as accurate to high velocity either because turbine adds too much resistance to flow.
A target flow meter and a differential pressure flow meter is not as accurate, especially flow is slow, because signal deviations either generated by the strain sensors or generated in the amplifiers are amplified.
The present invention measures force such as force generated by fluid flow on a force sensor. It can be used to measure breathing of patients. It can be used to measure velocity and rate of gas and liquid in industries. The present invention costs less to manufacture due to simplicity. It is very accurate. It adds less resistance to fluid flow.
The present invention can be bi-directional.
SUMMARY OF THE INVENTIONThe present invention directly measures breathing airflow instead of measuring the resistance of the chest. The objective of the present invention is to increase sensitivity of apnea monitor. Another objective is to measure vital capacity. The present invention collects parameters about breathing. Based on the parameters, vital capacity can be calculated. The parameters will also help in diagnoses.
External force of fluid flow acting on the force sensor can be expressed as
F=cd v2 At/2
where
-
- F=external force (N)
- c=overall force sensor coefficient obtained from empirical data
- d=density of fluid (kg/m3)
- v=fluid velocity (m/s)
- At=area of force sensor (square m)
When there is an external force to the force sensor, the force sensor is moved away from the original position. A proximity sensor measures the position deviation and generates a position signal. The proximity sensor can be optical, capacitive, inductive, and more. The position signal is amplified to electric current by an electronic unit The electric current drives an electromagnet means of anti-force to generate an anti-force. The anti-force acts on the force sensor to prevent the force sensor from moving away from the original position. When the torque made by the electromagnet means of anti-force is equal to the torque made by the external force, the force sensor stops moving. The position deviation, the position signal, the electric current, and the anti-force form a closed loop system of negative feedback. A display unit measures the electric current and converts the value of electric current to value of force. The position deviation, the position signal, the electric current, and the anti-force form a closed loop of negative feedback.
Claims
1. A force meter for measuring external force comprising:
- A) A case;
- B) A force sensor, said force sensor moves away from an original position when an external force is applied to said force sensor;
- C) A proximity sensor, said proximity sensor measures a position deviation of said force sensor from said original position, said proximity sensor generates a position signal when a position deviation is detected, the larger said position deviation is the stronger said position signal is;
- D) An electromagnetic means of anti-force, said electromagnetic means of anti-force generates an anti-force to move said force sensor backwards to said original position while receiving an electric current, the stronger said electric current is the stronger said anti-force is;
- E) An electronic unit, said electronic unit generates said electric current while receiving said position signal, the stronger said position signal is the stronger said electric current is;
- F) A display unit, said display unit measures value of said electric current, said display unit converts value of said electric current to value of force, or other value related to force before displaying.
2. A force meter in claim 1, wherein said position deviation, said position signal, said electrical current, and said anti-force form a closed loop system of negative feedback that is preventing increment of said position deviation, while an external force is increasing said position deviation.
3. A force meter in claim 1, wherein said proximity sensor comprises a optical proximity sensor.
4. A force meter in claim 3, wherein said optical proximity sensor comprises at least a light controller, at least a light source, and at least a light sensor, said light source and said light sensor are secured to said case, said light controller is secured to said force sensor, said light controller moves between said light source and said light sensor to change light energy rate from said light source to said light sensor when the position of said force sensor changes.
5. A force meter in claim 1, wherein said electronic unit comprises a proportional-integral-derivative controller.
6. A force meter in claim 1, wherein said electromagnetic means of anti-force comprises a magnetic reset structure, an axle, at least a balance weight, at least a movable magnetic, and at least a fixed coil, said movable magnetic, interacting with said electric current in said fixed coils, generate said anti-force, said balance weight makes the central weight of an assembly at or near the central line of said axle, said movable magnetic are secured to said axle, said fixed coils are electrically connected to said electronic unit so that said electric current can go through said fixed coils, said fixed coils are secured to said case, said assembly comprises said movable magnetic, said force sensor, said axle, said balance weight, and said light controller.
7. A force meter in claim 6, wherein said magnetic reset structure comprises a reset magnet, said reset magnet is secured to said case, said reset magnet interacts with said movable magnetic to generate a torque rotating said force sensor to said original position when there is no external force.
8. A force meter in claim 1, wherein said electromagnetic means of anti-force comprises, at least a fixed magnet, a coil axle, a coil balance weight for making the central weight of a coil assembly at or near the central line of said coil axle, a movable coil, a means of electrical connection for said movable coil, said fixed magnets retract with said electric current in said movable coil to generate said anti-force, said fixed magnets are secured to said case, said movable coil is secured to said coil axle, said coil assembly comprises said movable coil, said force sensor, said coil axle, said coil balance weight, and said light controller.
9. A force meter in claim 8, wherein said means of electrical connection comprises at least two reset springs or two reset gossamer, said reset springs mechanically connect said coil assembly to said case to rotate said force sensor to said original position when there is no external force, said movable coil is electrically connected to said electronic unit through said two reset springs to receive said electric current.
Type: Grant
Filed: Apr 1, 2010
Date of Patent: Mar 12, 2013
Patent Publication Number: 20110245706
Inventor: Guixian Lu (Pontiac, MI)
Primary Examiner: Lisa Caputo
Assistant Examiner: Jamel Williams
Application Number: 12/798,240
International Classification: G01F 1/42 (20060101); A61B 5/08 (20060101);